A symbol plotted at (lon,lat) on a 360-degree periodic map (e.g. Mercator, Mollweide, etc.) may be clipped by the boundary and should appear at the other side. To visualize, consider a 1 cm diameter circle plotted at lon = 1 on Equator, with -R0/360. Part of that circle may be clipped by the west = 0 boundary, However, that boundary is periodic so the clipped part of the circle should appear at the east = 360 boundary. We discussed a solution to this via email, now entered here for reference:

If projection is among cylindrical, conical and miscellaneous, or linear with degrees, and w-e == 360, then we must plot symbols twice, with clipping on:

First at the given plot_x, plot_y locationSecond at the repeating point which is outside the map region.if (lon-west) > 180 plot to left of west boundary else plot to right of east boundary

The only complication I see is if user wants -N. Perhaps we should expand -N to take some options:

-N No clip and show those repeating symbols if test above passes [Default]-Nr No clip and no repeating symbols-Nc Retain clipping but do not deal with repeating symbols

I can imagine -Nc be useful when plotting millions of smaller symbols and we don't want to plot 2 millions needlessly.